1. Field of the Invention
This invention relates broadly to a system for bone fracture fixation. More particularly, this invention relates to a system and method for fixation pin stabilization within a fractured bone.
2. State of the Art
Metacarpal fractures are very common. Immobilization of the metacarpal bone on either side of the fracture is imperative for proper healing. However, the location of the fracture presents several difficulties to ideal immobilization.
The most frequently used treatments for immobilizing the fracture are splinting and casting. However, due to the location of the metacarpal bones, these treatments fail to maintain proper fracture reduction in the metacarpal bones. Strong fixation is possible with techniques using plates, fixation screws, and fixation pins attached to the affected bones through operative treatment. While these types of fracture reduction devices are commonly used in larger bone fractures, e.g., ulnar, tibial, or femoral fractures, such operative treatment generally implies a formidable incision and exposure of the fracture site. Therefore, these techniques are often judged to be too invasive for the relatively small and fragile metacarpal bones.
An alternative less invasive technique has been used in which a small incision is made in the skin proximal the metacarpal bone, a boring tool is inserted through the incision and is used to drill a small hole into the metacarpal bone, the boring tool is removed, and then the physician feeds the pin through the incision and into the small unseen bore in the bone. However, feeding the pin through the skin is often a blind operation with no manner provided for indicating to the physician the relative location of the pin and the small hole bored in the bone. As such, the technique is objectionable to both physician and patient as blind feeding can result in exacerbating damage to the surrounding tissue. In addition, the implanted pin fails to provide torsional fixation for fractures which need to be rotationally immobilized. Similar problems exist with respect to metatarsal and phalangeal fractures.
Co-owned U.S. Pat. Nos. 6,200,321 and 6,273,892, which are hereby incorporated by reference herein in their entireties but which are not admitted as prior art hereto, disclose systems for inserting pins into a metacarpal, metatarsal, phalangeal, and other small bones without the drawbacks associated with blind pin insertion. In addition, U.S. Pat. No. 6,273,892 discloses a collet which can be used to provide torsional fixation of an implanted pin. However, the collet is small and difficult to handle, requires a relatively large bone mass permitting an end of the collet to be tapped into the bone, and is relatively time consuming to implant. As such, it would be desirable to have a device which provides stabilization for an implanted pin, but which overcomes the stated drawbacks of the prior device.
It is therefore an object of the invention to provide a device which locks a fixation pin in the metacarpal, metatarsal, or phalangeal bones, or bones of similar structure.
It is another object of the invention to provide a device which provides torsional and longitudinal stability to the fixation pin and thereby to the bone through which the fixation pin extends.
It is also an object of the invention to provide a device which can be implanted relatively easily and quickly.
It is a further object of the invention to provide a fracture fixation system which provides a fixation system which is relatively easy to manipulate.
In accord with these objects, which will be discussed in detail below, a locking device including a locking sleeve and a handle is provided. The locking sleeve is preferably a metal tubular cylindrical member having a longitudinal axis and defining a channel parallel to the axis. The cylindrical member has a diameter sized to receive a first portion of a fixation pin, and preferably a plurality of resilient locking catches adapted to hold a second portion of the fixation pin angled relative to the first portion. The distal end of the sleeve includes a tip which is preferably provided with a distalmost cutting edge and an adjacent pin guide adapted to be located about a portion of the diameter of a fixation pin. The handle is coupled to the proximal end of the sleeve to facilitate manipulation of the sleeve.
The locking sleeve is used to stabilize the location and orientation of a fixation pin implanted in a bone. Such an implanted pin has a central portion which extends across the fracture, a distal end which extends preferably to the distal end of the medullary canal of the bone, and a proximal portion which protrudes from the proximal end of the bone and above the skin surface. The proximal portion is angled relative to the central portion along a bent portion therebetween.
According to the invention, the distal end of the locking sleeve is fed over the proximal end of the pin and then manipulated with the handle such that the guide portion of the distal end of the sleeve is placed against the pin with the cutting edge against the skin. The cutting edge is then pushed to pierce the skin, pass through the tissue in the hand, and enter the bone surrounding the existing entry hole used for pin insertion. As the locking sleeve is pushed into the tissue and bone, the resilient catches of the sleeve are pushed over the bent portion of the pin (generally at the intersection of the central and proximal portions), with the bent portion effectively snap fitting between longitudinally adjacent catches as the sleeve is moved thereover. The sleeve is pushed into the bone until sufficiently seated for stabilized support, e.g., with the cutting edge extending from one side of the medullary canal, across the canal, and into the bone on the opposite side until it meets the cortex. The sleeve and pin are then preferably cut below the skin. Thus, the sleeve implanted in the bone stabilizes the pin during healing of the fracture.
If more than one pin is used to stabilize a fracture, a locking sleeve may be used for each pin.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.